Movable body apparatus, pattern formation apparatus and exposure apparatus, and device manufacturing method

ABSTRACT

On the +X and −X sides of a projection unit, a plurality of Z heads are arranged in parallel to the X-axis, by a predetermined distance half or less than half the effective width of the Y scale so that two Z heads each constantly form a pair and face a pair of Y scales. Of the pair of heads consisting of two Z heads which simultaneously face the scale, measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to malfunction of the head, measurement values of the other head is used, and the positional information of the stage in at least the Z-axis direction can be measured in a stable manner and with high precision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of ProvisionalApplication No. 60/996,248 filed Nov. 7, 2007, the disclosure of whichis hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body apparatus, patternformation apparatus and exposure apparatus, and device manufacturingmethods, and more particularly, to a movable body apparatus equippedwith a movable body which substantially moves along a predeterminedplane, a pattern formation apparatus which forms a pattern on an objectmounted on a movable body, an exposure apparatus which forms a patternon an object by irradiating an energy beam, and a device manufacturingmethod which uses the exposure apparatus.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing electrondevices (microdevices) such as semiconductor devices (such as integratedcircuits) and liquid crystal display devices, exposure apparatuses suchas a projection exposure apparatus by a step-and-repeat method (aso-called stepper) and a projection exposure apparatus by astep-and-scan method (a so-called scanning stepper (which is also calleda scanner) are mainly used.

However, the surface of a substrate subject to exposure such as a wafer,a glass plate or the like (hereinafter generally referred to as a wafer)is not always flat, for example, by undulation and the like of thewafer. Therefore, especially in a scanning exposure apparatus such as ascanner and the like, when a reticle pattern is transferred onto a shotarea on a wafer by a scanning exposure method, positional information(focus information) related to an optical axis direction of a projectionoptical system of the wafer surface is detected at a plurality ofdetection points set in an exposure area, for example, using a multiplepoint focal point position detection system (hereinafter also referredto as a “multipoint AF system”) and the like, and based on the detectionresults, a so-called focus leveling control is performed (for example,U.S. Pat. No. 5,448,332) to control the position in the optical axisdirection and the inclination of a table or a stage holding a wafer sothat the wafer surface constantly coincides with an image plane of theprojection optical system in the exposure area (the wafer surface iswithin the focal depth of the image plane).

Further, with the stepper or the scanner and the like, wavelength ofexposure light used with finer integrated circuits is becoming shorteryear by year, and numerical aperture of the projection optical system isalso gradually increasing (higher NA), which improves the resolution.Meanwhile, due to shorter wavelength of the exposure light and higher NAin the projection optical system, the depth of focus had becomeextremely small, which caused a risk of focus margin shortage during theexposure operation. Therefore, as a method of substantially shorteningthe exposure wavelength while substantially increasing (widening) thedepth of focus when compared with the depth of focus in the air, theexposure apparatus that uses the immersion method has recently begun togather attention (refer to, U.S. patent Application Publication No.2005/0259234).

However, in the exposure apparatus using this liquid immersion method orother exposure apparatus whose distance (working distance) between thelower end surface of the projection optical system and the wafer issmall, it is difficult to place the multipoint AF system in the vicinityof the projection optical system. Meanwhile, in the exposure apparatus,in order to realize exposure with high precision, performing the focusleveling control described above with high precision in a stable manneris required.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda first movable body apparatus including a movable body whichsubstantially moves along a predetermined plane, the apparatuscomprising: a reflection surface which is arranged at one of the movablebody and the outside of the movable body, with a first direction withina plane parallel to the predetermined plane serving as a longitudinaldirection, and having a predetermined width in a second directionorthogonal to the first direction; and a measurement device whichmeasures positional information of the movable body in a third directionorthogonal to the predetermined plane at a plurality of measurementpoints placed on the reflection surface, whereby the placement of theplurality of measurement points is decided so that of the plurality ofmeasurement points, n points (wherein, n is an integer of two or more)or more are positioned within the predetermined width on the reflectionsurface, and when the movable body is at a predetermined position, n+1or more of the plurality of measurement points are positioned to bewithin the predetermined width on the reflection surface.

According to this apparatus, of the plurality of measurement points thatthe measurement device has, n points (wherein, n is an integer of two ormore) or more are positioned within the predetermined width on thereflection surface, and when the movable body is at a predeterminedposition, n+1 points or more are positioned within the predeterminedwidth on the reflection surface, Therefore, it becomes possible tomeasure positional information of the movable body in the thirddirection orthogonal to the predetermined plane in at least onemeasurement point. Accordingly, even if abnormality occurs in a part ofthe measurement of n points positioned within the predetermined width onthe reflection surface or n+1 points when the movable body is at thepredetermined position, it becomes possible to measure the positionalinformation of the movable body in the third direction, unfailingly,with the remaining measurement points.

According to a second aspect of the present invention, there is provideda second movable body which substantially moves along a predeterminedplane, the apparatus comprising: a reflection surface which is arrangedat one of the movable body and the outside of the movable body, with afirst direction within a plane parallel to the predetermined planeserving as a longitudinal direction, and having a predetermined width ina second direction orthogonal to the first direction; and a measurementdevice which measures positional information of the reflection surfacein a third direction orthogonal to the predetermined plane at aplurality of measurement points placed on the reflection surface,whereby the measurement device has a plurality of head sets including afirst head which irradiates a measurement beam on a first measurementpoint and a second head which irradiates a measurement beam on the firstmeasurement point or in its vicinity.

According to this apparatus, the measurement device has a plurality ofhead sets including a first head which irradiates a measurement beam ona first measurement point of the plurality of measurement points thatthe measurement device has, and a second head which irradiates ameasurement beam on the first measurement point or in its vicinity.Therefore, of the first head and the second head included in the headset, even if abnormality occurs in one of the heads, because the otherhead can be used, the head set stably irradiates measurement beams onthe scale and measures the positional information of the movable body inthe third direction orthogonal to the predetermined plane. Accordingly,by using the measurement device which has the plurality of head sets, itbecomes possible to unfailingly measure the positional information ofthe movable body in the third direction.

According to a third aspect of the present invention, there is provideda third movable body apparatus including a movable body whichsubstantially moves along a predetermined plane, the apparatuscomprising: a measurement device which measures positional informationof the movable body in a direction orthogonal to the predeterminedplane, at a plurality of measurement points placed in a movement rangeof the movable body, whereby the measurement device has a plurality ofheads which generate measurement information by irradiating ameasurement beam on at least one of the plurality of measurement pointswhen the movable body is located at a predetermined position.

According to this apparatus, the measurement device has a plurality ofheads which generate measurement information by irradiating ameasurement beam on at least one of the plurality of measurement pointswhen the movable body is located at a predetermined position. Therefore,it becomes possible to measure positional information of the movablebody in the third direction orthogonal to the predetermined plane usingat least one head. Accordingly, even if abnormality occurs in a part ofthe plurality of heads, it becomes possible to measure the positionalinformation of the movable body unfailingly in the third directionwithin the predetermined plane, using another head in the remainingheads.

According to a fourth aspect of the present invention, there is provideda pattern formation apparatus that forms a pattern on an object, theapparatus comprising: a patterning device which forms a pattern on theobject, and the movable body apparatus according to the presentinvention (to be precise, any one of the first, second, or third movablebody apparatus) in which the object is mounted on the movable body.

According to this apparatus, a pattern is generated by the patterningdevice on the object, which is mounted on a movable body that configuresa part of the movable body apparatus of the present invention and canunfailingly measure the position information in the third directionorthogonal to the predetermined plane Accordingly, it becomes possibleto form a pattern on the object with good precision.

According to a fifth aspect of the present invention, there is providedan exposure apparatus that forms a pattern on an object by irradiatingan energy beam, the apparatus comprising: a patterning device thatirradiates the energy beam on the object; the movable body apparatusaccording to the present invention in which the object is mounted on themovable body, and a driver which drives the movable body to make theobject relatively move with respect to the energy beam.

According to this apparatus, to make the object relatively move withrespect to the energy beam irradiated on the object from the patterningdevice, the driver drives the movable body on which the object ismounted with good precision. Accordingly, it becomes possible to form apattern on the object with good precision by scanning exposure.

According to a sixth aspect of the present invention, there is provideda device manufacturing method which uses the exposure apparatusaccording to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a view schematically showing the configuration of an exposureapparatus related to an embodiment;

FIG. 2A is a planar view showing a wafer stage, and FIG. 2B is a planarview showing a measurement stage;

FIG. 3 is a view used to explain a placement of measurement axes of aninterferometer system of the exposure apparatus in FIG. 1, and is aplanar view of a stage device is, partially omitted;

FIG. 4 is a view showing a placement of various measurement systemswhich the exposure apparatus in FIG. 1 is equipped with;

FIG. 5 is a view showing a placement of an encoder head (an X head and aY head) and an alignment system;

FIG. 6 is a view showing a placement of a Z head and a multipoint AFsystem;

FIG. 7 is a block diagram showing a main configuration of a controlsystem of the exposure apparatus in FIG. 1;

FIG. 8 is a view used to describe position measurement of a wafer tablein a Z-axis direction and a tilt direction by a plurality of Z heads,and a switching of the Z heads;

FIGS. 9A to 9C are views used to explain focus mapping;

FIGS. 10A and 10B are views used to explain a first and second modifiedexample of the surface position measurement system, respectively;

FIGS. 11A and 11B are views used to explain a third and fourth modifiedexample of the surface position measurement system, respectively, and

FIG. 12 is a view used to explain other modified examples of the surfaceposition measurement system.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described below, withreference to FIGS. 1 to 9C.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 inthe embodiment. Exposure apparatus 100 is a projection exposureapparatus by the step-and-scan method, or a so-called scanner. Asdiscussed later on, in the embodiment, a projection optical system PL isarranged, and in the description below, a direction parallel to anoptical axis AX of projection optical system PT will be described as the3-axis direction, a direction within a plane orthogonal to the Z-axisdirection in which a reticle and a wafer are relatively scanned will bedescribed as the Y-axis direction, a direction orthogonal to the Z-axisand the Y-axis will be described as the X-axis direction, and rotational(inclination) directions around the X-axis, the Y-axis, and the 3-axiswill be described as θx, θy, and θz directions, respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST, a projection unit PU, a stage device 50 having awafer stage WST and a measurement stage MST, and a control system ofthese parts. Although a part of the configuration is different such asthe configuration of the encoder system which will be described lateron, as a whole, exposure apparatus 100 is configured similar to theexposure apparatus disclosed in the pamphlet of InternationalPublication No. 2007/097379 (and the corresponding U.S. patentApplication Publication No. 2008/0088843) previously described.Accordingly, in the description below, the explanation given for eachcomponent will be simplified, except when especially necessary.Incidentally, in FIG. 1, a wafer W is mounted on wafer stage WST.

Illumination system 10 includes a light source, an illuminanceuniformity optical system, which includes an optical integrator and thelike, an illumination optical system that has a reticle blind and thelike (none of which are shown), as is disclosed in, for example, U.S.patent Application Publication No. 2003/0025890 and the like.Illumination system 10 illuminates a slit-shaped illumination area IAR,which is set on reticle R with a reticle blind (a masking system), by anillumination light (exposure light) IL with a substantially uniformilluminance. In this case, as illumination light IL, for example, an ArFexcimer laser beam (wavelength 193 nm) is used.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivablewithin an XY plane, for example, by a reticle stage drive section 11(not shown in FIG. 1, refer to FIG. 7) that includes a linear motor orthe like, and reticle stage RST is also drivable in a scanning direction(in this case, the Y-axis direction, which is the lateral direction ofthe page surface in FIG. 1) at a predetermined scanning speed.

The positional information (including rotation information in the θzdirection) of reticle stage RST in the XY plane (movement plane) isconstantly detected, for example, at a resolution of around 0.25 nm by areticle laser interferometer (hereinafter referred to as a “reticleinterferometer”) 116, via a movable mirror 15 (the mirrors actuallyarranged are a Y movable mirror (or a retro reflector) that has areflection surface which is orthogonal to the Y-axis direction and an Xmovable mirror that has a reflection surface orthogonal to the X-axisdirection). The measurement values of reticle interferometer 116 aresent to a main controller 20 (not shown in FIG. 1, refer to FIG. 7).

Projection unit PU is placed below reticle stage PST in FIG. 1.Projection unit PU includes a barrel 40, and projection optical systemPL that has a plurality of optical elements which are held in apredetermined positional relation inside barrel 40. As projectionoptical system PL, for example, a dioptric system is used, consisting ofa plurality of lenses (lens elements) that is disposed along an opticalaxis AX, which is parallel to the Z-axis direction. Projection opticalsystem PL is, for example, a both-side telecentric dioptric system thathas a predetermined projection magnification (such as one-quarter,one-fifth, or one-eighth times). Therefore, when illumination light ILfrom illumination system 10 illuminates illumination area IAR,illumination light IL that has passed through reticle R which is placedso that its pattern surface substantially coincides with a first plane(an object plane) of projection optical system PL forms a reduced imageof the circuit pattern (a reduced image of a part of the circuitpattern) of reticle R formed within illumination area IAR, viaprojection optical system PL (projection unit PU), in an area(hereinafter, also referred to as an exposure area) IA conjugate toillumination area IAR on wafer W whose surface is coated with a resist(a photosensitive agent) and is placed on a second plane (an imageplane) side of projection optical system PL. And by reticle stage RSTand wafer stage WST being synchronously driven, reticle R is relativelymoved in the scanning direction (the Y-axis direction) with respect toillumination area ITAR (illumination light IL) while wafer W isrelatively moved in the scanning direction (the Y-axis direction) withrespect to exposure area IA (illumination light IL), thus scanningexposure of a shot area (divided area) on wafer W is performed, and thepattern of reticle R is transferred onto the shot area. That is, in theembodiment, the pattern is generated on wafer W according toillumination system 10, reticle R, and projection optical system PL, andthen by the exposure of the sensitive layer (resist layer) on wafer Wwith illumination light IL, the pattern is formed on wafer W.

In exposure apparatus 100 of the embodiment, a local liquid immersiondevice B is installed to perform exposure by a liquid immersion method.Local liquid immersion device 8 includes a liquid supply device 5, aliquid recovery device 6 (both of which are not shown in FIG. 1, referto FIG. 7), a liquid supply pipe 31A, a liquid recovery pipe 31B, anozzle unit 32 and the like. As shown in FIG. 1, nozzle unit 32 issupported in a suspended state by a mainframe (not shown) holdingprojection unit PU, so that the periphery of the lower end portion ofbarrel 40 that holds an optical element closest to the image plane side(the wafer W side) constituting projection optical system PL, in thiscase, a lens (hereinafter also referred to as a tip lens) 191, isenclosed. In the embodiment, as shown in FIG. 1, nozzle unit 32 is setso that its lower end surface is on a substantially flush surface withthe lower end surface of tip lens 191. Further, nozzle unit 32 isequipped with a supply opening and a recovery opening of liquid Lq, alower surface to which wafer W is placed facing and at which therecovery opening is arranged, and a supply flow channel and a recoveryflow channel that are connected to a liquid supply pipe 31A and a liquidrecovery pipe 31B respectively. Liquid supply pipe 31A and liquidrecovery pipe 31B are slanted by around 45 degrees relative to an X-axisdirection and Y-axis direction in a planar view (when viewed from above)as shown in FIG. 4, and are placed symmetric to a straight line (areference axis) LV which passes through the center (optical axis AX ofprojection optical system PL, coinciding with the center of exposurearea IA previously described in the embodiment) of projection unit PUand is also parallel to the Y-axis.

Liquid supply pipe 31A connects to liquid supply device 5 (not shown inFIG. 1, refer to FIG. 7), and liquid recovery pipe 31B connects toliquid recovery device 6 (not shown in FIG. 1, refer to FIG. 7). In thiscase, in liquid supply device 5, a tank to store the liquid, acompression pump, a temperature controller, a valve for controlling theflow amount of the liquid, and the like are equipped. In liquid recoverydevice 6, a tank to store the liquid which has been recovered, a suctionpump, a valve for controlling the flow amount of the liquid, and thelike are equipped.

Main controller 20 controls liquid supply device 5 (refer to FIG. 7),and supplies liquid between tip lens 191 and wafer W via liquid supplypipe 31A, as well as control liquid recovery device 6 (refer to FIG. 7),and recovers liquid from between tip lens 191 and wafer W via liquidrecovery pipe 31B. During the operations, main controller 20 controlsliquid supply device 5 and liquid recovery device 6 so that the quantityof water supplied constantly equals the quantity of water which has beenrecovered. Accordingly, in the space between tip lens 191 and wafer W, aconstant quantity of liquid Lq (refer to FIG. 1) is held constantlyreplaced, and by this, a liquid immersion area 14 (for example, refer toFIG. 8) is formed. Incidentally, in the case measurement stage MST whichwill be described later on is positioned below projection unit PU,liquid immersion area 14 can be formed similarly in the space betweentip lens 191 and a measurement table described later on.

In the embodiment, as the liquid described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 nm) is to be used. Incidentally,refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shorted to around 134 nm.

As shown in FIG. 1, stage device 50 is equipped with a wafer stage WSTand a measurement stage MST placed above a base board 12, a measurementsystem 200 (refer to FIG. 7) which measures positional information ofthe stages WST and MST, a stage drive system 124 (refer to FIG. 7) whichdrives stages WST and MST and the like. Measurement system 200 includesan interferometer system 118, an encoder system 150, and a surfaceposition measurement system 180 as shown in FIG. 7. Incidentally,details on interferometer system 118, encoder system 150 and the likewill be described later in the description.

Wafer stage WST and measurement stage MST are supported above base board12, via a clearance of around several μm by a plurality of noncontactbearings (not shown) fixed to each of the bottom surfaces, such as, forexample, air pads. Further, stages WST and MST are drivableindependently within the XY plane, by stage drive system 124 (refer toFIG. 7) which includes a linear motor and the like.

Wafer stage WST includes a stage main section 91, and a wafer table WTBthat is mounted on stage main section 91. Wafer table WTS and stage mainsection 91 are configured drivable in directions of six degrees offreedom (X, Y, Z, θx, θy, and θz) with respect to base board 12 by adrive system including a linear motor and a Z leveling mechanism(including a voice coil motor and the like).

In the center of the upper surface of wafer table WTB, a wafer holder(not shown) is arranged which holds wafer w by vacuum suction or thelike. On the outer side of the wafer holder (mounting area of thewafer), as shown in FIG. 2A, a plate (a liquid repellent plate) 28 isarranged that has a circular opening one size larger than the waferholder formed in the center, and also has a rectangular outer shape(contour). A liquid repellent treatment against liquid Lq is applied tothe surface of plate 28 (a liquid repellent surface is formed).Incidentally, plate 28 is installed on the wafer table WTB uppersurface, so that its entire surface or a part of the surface becomesflush with the surface of wafer W.

Plate 28 has a first liquid repellent area 28 a having a rectangularouter shape (contour) with the circular opening described above formedin the center, and a second liquid repellent area 28 b having arectangular frame (loop) shape placed around the first liquid repellentarea. Incidentally, in the embodiment, because water is used as liquidLq as is previously described, hereinafter, the first liquid repellentarea 28 a and the second liquid repellent area 28 b will also bereferred to as a first water repellent plate 28 a and a second waterrepellent plate 28 b.

On an end on the +Y side of the first water repellent plate 28 a, ameasurement plate 30 is arranged. On measurement plate 30, a fiducialmark FM is arranged in the center, and a pair of aerial imagemeasurement slit patterns (slit-shaped measurement patterns) SL isarranged with the mark in between. And, in correspondence with eachaerial image measurement slit pattern SL, a light-transmitting system(not shown) which guides illumination light IL passing through the slitpatterns outside wafer stage WST (a photodetection system arranged inmeasurement stage MST which will be described later on) is arranged.

On second liquid repellent area 28 b, scales for an encoder system (tobe described later) are formed. More specifically, in areas on one sideand the other side in the X-axis direction of the second water repellentplate 28 b (both sides in the horizontal direction in FIG. 2A), Y scales39Y₁ and 39Y₂ are formed, respectively. Y scales 39Y₁ and 39Y₂ are eachcomposed of a reflective grating (for example, a diffraction grating)having a periodic direction in the Y-axis direction in which grid lines38 having the longitudinal direction in the X-axis direction are formedin a predetermined pitch along a direction parallel to the Y-axis (theY-axis direction). Similarly, in areas on one side and the other side inthe Y-axis direction of the second water repellent plate 28 b (bothsides in the vertical direction in FIG. 5A), X scales 39X₁ and 39X₂ areformed, respectively, in a state where the scales are placed between Yscales 39Y₁ and 39Y₂. X scales 39X₁ and 39X₂ are each composed of areflective grating (for example, a diffraction grating) having aperiodic direction in the X-axis direction in which grid lines 37 havingthe longitudinal direction in the Y-axis direction are formed in apredetermined pitch along a direction parallel to the X-axis (the X-axisdirection). The pitch of grid lines 37 and 38, for example, is set to 1μm. Incidentally, in FIG. 2A, the pitch of the gratings is illustratedlarger than the actual pitch for the sake of convenience. The same istrue also in other drawings.

Incidentally, in order to protect the diffraction grating, it is alsoeffective to cover the grating with a glass plate with low thermalexpansion that has water repellency. In this case, as the glass plate, aplate whose thickness is the same level as the wafer, such as forexample, a plate 1 mm thick, can be used, and the plate is set on theupper surface of wafer table WTB so that the surface of the glass platebecomes the same height (surface position) as the wafer surface.

Further, to the −Y end surface and the −X end surface of wafer tableWTB, mirror-polishing is applied, respectively, and as shown in FIG. 2A,reflection surfaces 17 a and 17 b are formed for interferometer system118 which will be described later in the description.

Measurement stage MST includes a stage main section 92 driven in the XYplane by a linear motor and the like (not shown), and a measurementtable MTB mounted on stage main section 92, as shown in FIG. 1.Measurement stage MST is configured drivable in at least directions ofthree degrees of freedom (X, Y, and θz) with respect to base board 12 bya drive system (not shown).

Incidentally, in FIG. 7, the drive system of wafer stage WST and thedrive system of measurement stage MST are included and are shown asstage drive system 124.

Various measurement members are arranged at measurement table MTB (andstage main section 92). As such measurement members, for example, asshown in FIG. 25, members such as an uneven illuminance measuring sensor94 that has a pinhole-shaped light-receiving section which receivesillumination light IL on an image plane of projection optical system PL,an aerial image measuring instrument 96 that measures an aerial image(projected image) of a pattern projected by projection optical systemPL, a wavefront aberration measuring instrument 98 by the Shack-Hartmanmethod that is disclosed in, for example, the pamphlet of InternationalPublication No. 2003/065428, an illuminance monitor (not shown) and thelike are employed. Further, in stage main section 92, a pair ofphotodetection systems (not shown) is arranged in a placement facing thepair of light-transmitting systems (not shown) previously described.

In the embodiment, in a state where wafer stage WST and measurementstage MST are in proximity within a predetermined distance in the Y-axisdirection (including a contact state), illumination lights IL that hasbeen transmitted through each aerial image measurement slit pattern SLof measurement plate on wafer stage WST axe guided by eachlight-transmitting system (not shown) and are received bylight-receiving elements of each photodetection system (not shown)within measurement stage MST.

On the −Y side end surface of measurement table MTB, a fiducial bar(hereinafter, shortly referred to as an “FD bar”) 46 is arrangedextending in the X-axis direction, as shown in FIG. 2B. In the vicinityof the end portions on one side and the other side in the longitudinaldirection of FD bar 46 r a reference grating (for example, a diffractiongrating) 52 whose periodic direction is the Y-axis direction isrespectively formed, placed symmetric to a center line CL. Further, onthe upper surface of FD bar 46, a plurality of reference marks M isformed As each of reference marks M, a two-dimensional mark having asize that can be detected by a primary alignment system and secondaryalignment systems (to be described later) is used. Incidentally, thesurface of FD bar 46 and the surface of measurement table MTB are alsocovered with a liquid repellent film (water repellent film).

On the +Y end surface and the −X end surface of measurement table MTB,reflection surfaces 19 a and 19 b are formed similar to wafer table WTBas is previously described (refer to FIG. 2B).

In exposure apparatus 100 of the embodiment, a primary alignment systemAL₁ having a detection center at a position spaced apart from opticalaxis AX of projection optical system PL at a predetermined distance onthe −Y side is placed on reference axis LV previously described as shownin FIGS. 4 and 5. Primary alignment system AL1 is fixed by the lowersurface of a (not shown) mainframe. On one side and the other side inthe X-axis direction with primary alignment system AL1 in between,secondary alignment systems AL2 ₁ and AL2 ₂, and AL2 ₃ and AL2 ₄ whosedetection centers are substantially symmetrically placed with respect tostraight line LV are severally arranged. Secondary alignment systems AL2₁ to AL2 ₄ are fixed via a movable support member to the lower surf aceof the mainframe (not shown), and by drive mechanisms 60 ₁ to 60 ₄(refer to FIG. 7), their detection areas (or detection center) can bedriven independently in the X-axis direction. Accordingly, the relativepositions of the detection areas of primary alignment system AL1 andsecondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are adjustablein the X-axis direction. Incidentally, a straight line (a referenceaxis) LA which passes through the detection center of primary alignmentsystem AL1 and is parallel to the X-axis shown in FIG. 4 and the likecoincides with the optical axis of a measurement beam 86 frominterferometer 127 previously described.

In the embodiment, as each of alignment systems AL1 and AL2 ₁ to AL2 ₄,for example, an FIA (Field Image Alignment) system by an imageprocessing method is used. The imaging signals from each of alignmentsystems AL1 and AL2 ₁ to AL2 ₄ are supplied to main controller 20, via asignal processing system (not shown).

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (for example, diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed.

Next, a configuration and the like of interferometer system 118 (referto FIG. 7), which measures the positional information of wafer stage WSTand measurement stage MST, will be described.

Interferometer system 118 includes a Y interferometer 16, Xinterferometers 126, 127, and 128 r and Z interferometers 43A and 43Bfor position measurement of wafer stage WST, and a Y interferometer 18and an X interferometer 130 for position measurement of measurementstage MST, as shown in FIG. 3. Y interferometer 16 and the three Xinterferometers 126, 127, and 128 each irradiate interferometer beams(measurement beams) B4 (B4 ₁, B4 ₂), B5 (B5 ₁, a B5 ₂), B6, and 37 onreflection surfaces 17 a and 17 b of wafer table WTB. And Yinterferometer 16 and the three X interferometers 126, 127, and 128 eachreceive the reflected lights, and measure the positional information ofwafer stage WST in the XY plane, and supply the positional informationwhich has been measured to main controller 20.

Incidentally, for example, X interferometer 126 irradiates at leastthree measurement beams parallel to the X-axis including a pair ofmeasurement beams B5 ₁ and B5 ₂ which passes through optical axis (inthe embodiment, also coinciding with the center of exposure area IApreviously described) AX of projection optical system PL and issymmetric about a straight line (reference axis LH (refer to FIGS. 4, 5and the like)) parallel to the X-axis. Further, Y interferometer 16irradiates at least three measurement beams parallel to the Y-axisincluding a pair of measurement beams B4 ₁ and B4 ₂ which is symmetricabout reference axis LV previously described on reflection surface 17 aand a movable mirror 41 (to be described later on). As described, in theembodiment, as each interferometer, a multiaxial interferometer which aplurality of measurement axis is used, with an exception for a part ofthe interferometers (for example, interferometer 128). Therefore, inaddition to the X, Y positions of wafer table WTB (wafer stage WST),main controller 20 can also compute rotation information (that is,pitching amount) in the θx direction, rotation information (that is,rolling amount) in the θy direction, and rotation information (that is,yawing amount) in the θz direction, based on the measurement results ofY interferometer 16 and either X interferometers 126 or 127.

Further, as shown in FIG. 1, movable mirror 41 having a concave-shapedreflection surface is attached to the side surface on the −Y side ofstage main section 91. As it can be seen from FIG. 2A, movable mirror 41is designed so that the length in the X-axis direction is longer thanreflection surface 17 a of wafer table WTB.

A pair of Z interferometers 43A and 43B are arranged (refer to FIGS. 1and 3), facing movable mirror 41. Z interferometers 43A and 43Birradiate two measurement beams B1 and B2, respectively, on fixedmirrors 47A and 478, which are fixed, for example, on a frame (notshown) supporting projection unit PU, via movable mirror 41. And byreceiving each reflected light, Z interferometers 43A and 43B measurethe optical path length of measurement beams B1 and B2. And from theresults, main controller 20 computes the position of wafer stage WST infour degrees of freedom (Y, Z, θy, and θz) directions.

In the embodiment, position information within the XY plane (includingthe rotation information in the θz direction) of wafer stage WST (wafertable WTB) is mainly measured by an encoder system (to be describedlater). Interferometer system 118 is used when wafer stage WST ispositioned outside the measurement area (for example, near unloadingposition UP and loading position LP as shown in the drawings such asFIG. 4) of the encoder system. Further, interferometer system 118 isused secondarily when correcting (calibrating) a long-term variation(for example, temporal deformation of the scale) of the measurementresults of the encoder system and the like. As a matter of course, allpositional information of wafer stage WST (wafer table WTB) can bemeasured using both interferometer system 118 and the encoder systemtogether.

Y interferometer 18 and X interferometer 130 of interferometer system118 irradiate interferometer beams (measurement beams) on reflectionsurfaces 19 a and 19 b of measurement table MTB as shown in FIG. 3, andmeasure the positional information of measurement stage MST (including,for example, at least the positional information in the X-axis and theY-axis directions and the rotation information in the θz direction) byreceiving the respective reflected lights, and supply the measurementresults to main controller 20.

Next, the structure and the like of encoder system 150 (refer to FIG. 7)which measures the positional information of wafer stage WST in the XYplane (including rotation information in the θz direction) will bedescribed.

In exposure apparatus 200 of the embodiment, as shown in FIG. 4, fourhead units 62A to 62D are placed in a state extending from nozzle unit32 in four directions. These head units 62A to 62D are fixed to themainframe (not shown) holding projection unit UP in a suspended state,via a support member.

Head units 62A and 62C are equipped with a plurality of (nine, in thiscase) Y heads 65 ₁ to 65 ₉ and 64 ₁ to 64 ₉, as shown in FIG. 5,respectively. In detail, head units 62A and 62C are equipped with aplurality of (seven, in this case) Y heads 65 ₅ to 65 ₉ and 64 ₁ to 64 ₇placed at a distance WD on reference axis LH previously described,respectively, and a plurality of (two, in this case) Y heads 65 ₁ and 65₂, and 64 ₉ and 64 ₉ placed at distance WD a predetermined distance awayfrom reference axis LH in the −Y direction on the −Y side of nozzle unit32 in parallel with reference axis LH, respectively. Incidentally, thedistance between Y heads 65 ₂ and 65 ₃ and Y heads 64 ₇ and 64 ₈ in theX-axis direction is also set to WD. Hereinafter, Y heads 65 ₁ to 65 ₉and 64 ₁ to 64 ₉ will also be described as Y heads 65 and 64,respectively, as necessary.

Head unit 62A constitutes a multiple-lens (nine-lens, in this case) Ylinear encoder (hereinafter, shortly referred to as a “Y encoder” or an“encoder” as appropriate) 70A (refer to FIG. 7) that measures theposition of wafer stage WST (wafer table WTB) in the Y-axis direction (Yposition), using Y scale 39Y₁ previously described. Similarly, head unit62C constitutes a multiple-lens (nine-lens, in this case) Y linearencoder 70C (refer to FIG. 7) that measures the Y position of waferstage WST (wafer table WTB) using Y scale 39Y₂ described above. In thiscase, distance WD in the X-axis direction of the nine Y heads 64 and 65(to be more accurate, the irradiation points of the measurement beamsgenerated by Y heads 65 and 64 on the scale) that head units 62A and 62Care each equipped with, is set slightly narrower than the width (to bemore precise, the length of grid line 38) of Y scales 39Y₁ and 39Y₂ inthe X-axis direction. Accordingly, of each nine Y heads 65 and 64, atleast two heads each constantly face the corresponding Y scales 39Y₁ and39Y₂ at the time of the exposure. More specifically, of the measurementbeams which each nine Y heads 65 and 64 generate, at least twomeasurement beams each can be irradiated on the corresponding Y scales39Y₁ and 39Y₂.

As shown in FIG. 5, head unit 62B is placed on the +Y side of nozzleunit 32 (projection unit PU), and is equipped with a plurality of, inthis case, seven X heads 66 ₈ to 66 ₁₄ that are placed on reference axisLV previously described along Y-axis direction at distance WD. Further,head unit 62D is placed on the −Y side of primary alignment system AL1,on the opposite side of head unit 62B via nozzle unit 32 (projectionunit PU), and is equipped with a plurality of, in this case, seven Xheads 66 ₁ to 66 ₇ that are placed on reference axis LV at distance WD.Hereinafter, X heads 66 ₁ to 66 ₁₄ will also be described as X heads 66,as necessary.

Head unit 62B constitutes a multiple-lens (seven-lens, in this case) Xlinear encoder (hereinafter, shortly referred to as an “X encoder” or an“encoder” as needed) 703 (refer to FIG. 7) that measures the position inthe X-axis direction (the X-position) of wafer stage WST (wafer tableWTB) using X scale 39X₁ previously described. Further, head unit 62Dconstitutes a multiple-lens (seven-lens, in this case) X linear encoder70D (refer to FIG. 7) that measures the X-position of wafer stage WST(wafer table WTB) using X scale 39X₂ previously described.

Here, distance WD between adjacent X heads 66 (to be more accurate, theirradiation point of the measurement beam generated by X head 66 on thescale) in the Y-axis direction that are equipped in each of head units62B and 62D is set shorter than halt the width of X scales 39X₁ and 39X₂(to be more accurate, the length of grid line 37) in the Y-axisdirection. Accordingly, of the X heads 66 which head units 62B and 62Dare equipped with, at least two heads face the corresponding X scales39X₁ and 39X₂ at the time of the exposure and the like, except for timessuch as switching (linkage) which will be described later. Morespecifically, of the measurement beams which each seven X heads 66generate, at least two measurement beams each can be irradiated on thecorresponding X scales 39X₁ and 39X₂. Incidentally, the distance betweenX head 66 ₈ farthest to the −Y side of head unit 62B and X head 66 ₇farthest to the +Y side of head unit 62D is set slightly narrower thanthe width of wafer table WTB in the Y-axis direction so that switching(linkage described below) becomes possible between the two X heads bythe movement of wafer stage WST in the Y-axis direction.

Incidentally, in the placement of X head 66 in the embodiment, on theswitching (linkage) described above, only X head 66 ₈ farthest to the −Yside among X heads 66 belonging to head unit 62B faces the correspondingX scale 39X₁, and only X head 66 ₇ farthest to the +Y side among X heads66 belonging to head unit 62D fates the corresponding X scale 39X₂. Morespecifically, only one each of the X heads 66 faces X scales 39X₁ and39X₂. Therefore, the distance between head unit 62B and 62D can benarrower than distance WD, and at least one of X heads 66 ₈ and 66 ₉ canbe made to face the corresponding X scales at the same time, as well asX head 66 ₈ and X head 66 ₇ which face the corresponding X scales alsoat the time of switching (linkage).

In the embodiment, furthermore, as shown in FIG. 4, head units 62E and62F are respectively arranged a predetermined distance away on the −Yside of head units 62C and 62A. These head units 62E and 62F are fixedto the mainframe (not shown) holding projection unit UP in a suspendedstate, via a support member.

Head unit 62E is equipped with seven Y heads 67 ₁ to 67 ₇, as shown inFIG. 5. More particularly, head unit 62E is equipped with five Y heads67 ₁ to 67 ₅ placed on the −X side of the secondary alignment system AL2₁ on reference axis LA at substantially the same distance as distance WDpreviously described, and two Y heads 67 ₆ and 67 ₇ placed on the +Yside of the secondary alignment system AL2 ₁ a predetermined distanceaway in the +Y direction from reference axis LA, at distance WD parallelto reference axis LA. Incidentally, the distance between Y heads 67 ₅and 67 ₆ in the X-axis direction is also set to WD. Hereinafter, Y heads67 ₃ to 67 ₇ will also be described, appropriately, as Y head 67.

Head unit 62F is symmetrical to head unit 62E with respect to referenceaxis LV previously described, and is equipped with seven Y heads 681 to687 which are placed in symmetry to the seven Y heads 67 with respect toreference axis LV. Hereinafter, Y heads 68, to 687 will also bedescribed, appropriately, as Y head 68.

On alignment operation and the like, at least two each of Y heads 67 and68 face Y scales 39Y₂ and 39Y₁, respectively. More specifically, of themeasurement beams which each seven Y heads 67 and 68 generate, at leasttwo measurement beams each can be constantly irradiated on Y scales 39Y₁and 39X₂ at the time of alignment and the like. The Y position (and θzrotation) of wafer stage WST is measured by these Y heads 67 and 68(more specifically, Y encoders 70E and 70F configured by Y heads 67 and68).

Further, in the embodiment, at the time of baseline measurement and thelike of the secondary alignment system, Y head 67 ₅ and 68 ₃ which areadjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in theX-axis direction face the pair of reference gratings 52 of FD bar 46,respectively, and by Y heads 67 and 68 that face the pair of referencegratings 52, the Y position of FD bar 46 is measured at the position ofeach reference grating 52. In the description below, the encodersconfigured by Y heads 67 and 68 which face a pair of reference gratings52, respectively, are referred to as Y linear encoders (also shortlyreferred to as a “Y encoder” or an “encoder” as needed) 70E₂ and 70F₂.Further, for identification, Y encoders 70E and 70F configured by Yheads 67 and 68 that face Y scales 39Y₂ and 39Y₁ described above,respectively, will be referred to as Y encoders 70E₁ and 70F₁.

The measurement values of linear encoders 70A to 70F described above issupplied to main controller 20, and main controller 20 controls theposition within the XY plane of wafer stage WST based on threemeasurement values of linear encoders 70A to 70D or on three measurementvalues of encoders 70B, 70D, 70E₁, and 70F₁, and also controls therotation in the an direction of FD bar 46 based on the measurementvalues of linear encoders 70E₂ and 70F₂.

In exposure apparatus 100 of the embodiment, as shown in FIGS. 4 and 6,a multipoint focal position detecting system (hereinafter, shortlyreferred to as a “multipoint AF system”) by an oblique incident methodis arranged, which is composed of an irradiation system 90 a and aphotodetection system 90 b, having a configuration similar to the onedisclosed in, for example, U.S. Pat. No. 5,448,332 and the like. In theembodiment, as an example, irradiation system 90 a is placed on the +Yside of the −X end portion of head unit 62E previously described, andphotodetection system 90 b is placed on the +Y side of the +X endportion of head unit 62F previously described in a state of opposingirradiation system 90 a. The multipoint AF system (90 a, 90 b) is fixedto the lower surface of the mainframe (not shown) holding projectionunit PU previously described.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected. In the embodiment, the plurality of detectionpoints are placed, for example, in the arrangement of a matrix havingone row and M columns (M is a total number of detection points) orhaving two rows and N columns (N=M/2). In FIGS. 4 and 6, the pluralityof detection points to which a detection beam is severally irradiatedare not individually shown, but are shown as an elongate detection area(beam area) AF that extends in the X-axis direction between irradiationsystem 90 a and photodetection system 90 b. Because the length ofdetection area AF in the X-axis direction is set to around the same asthe diameter of wafer W, by only scanning wafer W in the Y-axisdirection once, position information (surface position information) inthe Z-axis direction across the entire surface of wafer W can bemeasured.

As shown in FIG. 6, in the vicinity of both end portions of beam area AFof the multipoint AF system (90 a, 90 b), heads 72 a and 72 b, and 72 cand 72 d of surface position sensors for Z position measurement(hereinafter, shortly referred to as “Z heads”) are arranged each in apair, in symmetrical placement with respect to reference axis LV. Zheads 72 a to 72 d are fixed to the lower surface of a main frame (notshown).

As Z heads 72 a to 72 d, for example, a head of an optical displacementsensor similar to an optical pickup used in a CD drive device is used. Zheads 72 a to 72 d irradiate measurement beams to wafer table WTB fromabove, and by receiving the reflected lights, measure the positionalinformation (surface position information) of the surface of wafer tableWTB in the Z-axis direction orthogonal to the XY plane at theirradiation point. Incidentally, in the embodiment, a configuration isemployed where the measurement beams of the Z heads are reflected by thereflection grating configuring the Y scales 39Y₂ and 39Y₂ previouslydescribed.

Furthermore, as shown in FIG. 6, head units 62A and 62C previouslydescribed are respectively equipped with Z heads 76 _(j) and 74 _(i) (i,j=1-9), which are nine heads each, at the same X position as Y heads 65_(j) and 64 _(i) (i, j=1-9) that head units 62A and 62C are respectivelyequipped with, with the Y position shifted. In this case, Z heads 76 ₈to 76 ₉ and 74 ₁ to 74 ₅, which are five heads each on the outer sidebelonging to head units 62A and 62C, respectively, are placed parallelto reference axis LH a predetermined distance away in the +Y directionfrom reference axis LH. Further, Z heads 76 ₁ and 76 ₂ and Z heads 74 ₈and 74 ₉, which are two heads on the innermost side belonging to headunits 62A and 62C, respectively, are placed on the +Y side of projectionunit PU, and the remaining Z heads 763 and 76 ₄, and 74 ₆ and 74 ₇ areplaced on the −Y side of Y heads 65 ₃ and 65 ₄, and 64 ₆ and 64 ₇,respectively. And Z heads 76 _(j) and 74 _(i), which are nine heads eachbelonging to head units 62A and 62C, respectively, are placed symmetricto each other with respect to reference axis LV. Incidentally, as eachof the Z heads 76 _(j) and 74 _(i), an optical displacement sensor headsimilar to Z heads 72 a to 72 d described above is used.

The distance of the nine Z heads 76 and 74 (to be more accurate, theirradiation point of the measurement beam generated by the Z heads onthe scale) in the X-axis direction that are equipped in each of headunits 62A and 62C is set equal to distance WD of Y heads 65 and 64 inthe X-axis direction. Accordingly, similar to Y heads 65 and 64, of eachnine Z heads 76 _(j) and 74 _(i), at least two heads each constantlyface the corresponding Y scales 39Y₁ and 39Y₂ at the time of theexposure and the like. More specifically, of the measurement beams whicheach nine Z heads 76 _(j) and 74 _(i) generate, at least two measurementbeams each can be irradiated on the corresponding Y scales 39Y₁ and39Y₂.

Z heads 72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉ connect to maincontroller 20 via a signal processing/selection device 170 as shown inFIG. 7, and main controller 20 selects an arbitrary Z head from Z heads72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉ via signalprocessing/selection device 170 and makes the head move into anoperating state, and then receives the surface position informationdetected by the Z head which is in an operating state via signalprocessing/selection device 170. In the embodiment, a surface positionmeasurement system 180 (a part of measurement system 200) that measurespositional information of wafer stage WST in the Z-axis direction andthe direction of inclination with respect to the XY plane is configured,including Z heads 72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉, andsignal processing/selection device 170. Incidentally, in the descriptionbelow, Z heads 74 ₁ to 74 ₉ and 76 ₁ to 76 ₉ will appropriately bereferred to as Z heads 74 and 76, respectively.

Furthermore, in exposure apparatus 100, above reticle stage RST, a pairof reticle alignment detection systems 13A and 13B (not shown in FIG. 1,refer to FIG. 7) consisting of TTR (Through The Reticle) alignmentsystems which use lights of the exposure wavelength is arranged.Detection signals of reticle alignment detection systems 13A and 13B aresupplied to main controller 20 via an alignment signal processing system(not shown).

FIG. 7 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. Incidentally, in FIG. 7,various sensors such as uneven illuminance measuring sensor 94, aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are arranged at measurement stage MST arecollectively shown as a sensor group 99.

In exposure apparatus 100 of the embodiment, because the placement ofthe Y scales on wafer table WTB previously described and the placementof the z heads previously described were employed, as shown in FIG. 8,in the range where wafer stage WST moves for exposure operation, Z heads76 and 74 which belong to head units 62A and 62C face Y scales 39Y₁ and39Y₂, respectively, without fail. Incidentally, in FIG. 8, the Z headswhich face the corresponding Y scales are shown circled by a solid line.

As previously described, head units 62A and 62C constantly make at leasttwo Z heads face the corresponding Y scale (to be more precise, at leasttwo measurement beams can be constantly irradiated on the correspondingscale). Therefore, main controller 20 pairs at least two Z heads facingthe Y scale and uses the pairs for head units 62A and 62C, respectively.Then, main controller 20 constantly monitors the measurement values ofthe two Z heads, and uses one of the measurement values as arepresentative of the pair of heads (or the head unit to which the two Zheads belong). Of the two Z heads, main controller 20, for example, usesthe head which faces the scale first as a priority head, and the headwhich faces the scale later on as an auxiliary head. Or, main controller20 can use the head near the center of the scale in a directionorthogonal to the longitudinal direction as a priority head, and theremaining head can be used as an auxiliary head. Main controller 20 cannormally use the measurement values of the priority head as arepresentative, and in the case abnormality occurs in the measurementvalues of the priority head, the measurement values of the auxiliaryhead can be used as the measurement values of the pair of heads (or headunit) in the Z-axis direction. Main controller 20 monitors themeasurement values of the two head units 62A and 62C in the Z-axisdirection according to this handling.

Main controller 20 monitors photoelectric conversion signals output by alight receiving element inside the head to inspect the correctness ofthe measurement result of the priority head, especially to inspect theoutput abnormality of the priority head due to malfunction (abnormality)of the head, and when there are no photoelectric conversion signals(when the signal intensity is zero) or when the signal intensity is atan extremely low level, main controller 20 judges that abnormality hasoccurred, and otherwise decides it is normal.

Therefore, in the range where wafer stage WST moves for exposureoperation, by controlling each motor that configures stage drive system124 based on the measurement results of the two head units 62A and 62C(the Z heads belonging to each unit), position of wafer stage WST in theZ-axis direction (the surface position of wafer table WTB) and theposition of tilt direction (position in the θy direction) can becontrolled in a stable manner and with high precision.

Further, when main controller 20 drives wafer stage WST in the X-axisdirection as shown by an outlined arrow in FIG. 8, the pair of Z heads76 and 74, which measures the surface position of wafer stage WST, issequentially switched to an adjacent pair of heads as shown by an arrowf1 in FIG. 8. To enter the details, as for Z head 76, the pair of headsis switched from the pair 76 ₄ and 76 ₅ surrounded by the circle in asolid line to the pair 76 ₅ and 76 ₆ surrounded by the circle in adotted line, and as for Z head 74, the pair of heads is switched fromthe pair 74 ₄ and 74 ₅ surrounded by the circle in a solid line to thepair 74 ₅ and 74 ₆ surrounded by the circle in a dotted line. In thiscase, one head (76 ₅, 74 ₅) is common in the pair of heads before theswitching and the pair of heads after the switching.

In the embodiment, in order to perform the switching (linkage) of the Zheads 76 and 74 smoothly, as is previously described, of the Z heads 76and 74 that head units 62A and 62C are equipped with, the distance(twice the distance WD of adjacent heads in the X-axis direction)between the two heads to be switched (for example, in the example inFIG. 8, Z heads 76 ₄ and 76 ₆, and 74 ₄ and 74 ₆) is set smaller thanthe width of Y scales 39Y₁ and 39Y₂ in the X-axis direction. In otherwords, distance WD of adjacent Z heads is set it is narrower than halfthe width of Y scales 39Y₁ and 39Y₂ in the X-axis direction.

In the embodiment, a method is employed where the head used formeasuring the Z position of wafer stage WST is switched from a pair ofheads (for example, Zh1 and Zh2) to another pair of heads (Zh2 and Zh3)including one of the heads (Zh2), with the movement of wafer stage WST.However, as well as this method, a modified method of switching toanother pair of heads (Zh3 and Zh4) which does not include a common headfrom a certain pair of heads (for example, Zh1 and Zh2) can be adopted.Also in this modified method, similar to the method described above, themeasurement values of the priority head should be used normally, and atthe time of abnormality, the measurement values of the auxiliary headshould be used representatively as the measurement values of the pair ofheads (or the head unit to which these heads belong).

Incidentally, as the cause of abnormality being generated in themeasurement values of the Z heads, there is two major causes, that is, acause coming from malfunction of the head, and a cause coming fromabnormality of the reflection surface (in the embodiment, a scale) onwhich the measurement beam is irradiated. As an example of the formercase, a mechanical failure of the head can be representatively given. Tobe concrete, a failure in the head itself, a failure in the measurementbeam light source, a situation where water droplets adhere on the headand the like can be given. A situation where the intensity of themeasurement beam becomes extremely low, if not the measurement beamlight source fails to operate, can be said to be a cause coming from thehead. Meanwhile, as an example of the latter case, the case can be givenin which the liquid of the liquid immersion area remains or foreignmaterials such as dust and the like adheres on the surface of the scale(reflection surface), and the measurement beam scans the remainingliquid or the adhered foreign material.

The method in the embodiment in which a pair of heads configured by apriority head and an auxiliary head is made to constantly face at leastone corresponding scale is effective not only to abnormality of themeasurement values due to malfunction of the heads, but also effectiveto abnormality of the measurement values due to abnormality in thescales.

Next, detection of position information (surface position information)of the wafer W surface in the Z-axis direction (hereinafter, referred toas focus mapping) that is performed in exposure apparatus 100 of theembodiment will be described. In the state of FIG. 9A, a straight line(centerline) parallel to the Y-axis that passes through the center ofwafer table WTB (which substantially coincides with the center of waferW) coincides with reference axis LV previously described.

On this focus mapping, as is shown in FIG. 9A, main controller 20controls the position within the XY plane of water table WTB based onthe measurement values of one (X linear encoder 70D) of the two X heads66 (surrounded by an elongated circle) facing X scale 39X₂, and apredetermined one (Y linear encoders 70F₁ and 70E₁) of the Y heads 68and 67 (surrounded by elongated circles), which are two heads each,facing Y scales 39Y₁ and Y₂, respectively. In the state of FIG. 9A, astraight line (centerline) parallel to the Y-axis that passes throughthe center of wafer table WTB (which substantially coincides with thecenter of wafer W) coincides with reference axis LV previouslydescribed.

Then, in this state, main controller 20 starts scanning of wafer stageWST in the +Y direction, and after having started the scanning,activates (turns ON) both Z heads 72 a to 72 d and the multipoint AFsystem (90 a, 90 b) by the time when wafer stage WST moves in the +Ydirection and detection beams of the multipoint AF system (90 a, 90 b)begin to be irradiated on wafer W.

Then, in a state where Z heads 72 a to 72 d and the multipoint AF system(90 a, 90 b) simultaneously operate, as is shown in FIG. 9B, positioninformation (surface position information) of the wafer table WTBsurface (surface of plate 28) in the Z-axis direction that is measuredby Z heads 72 a to 72 d and position information (surface positioninformation) of the wafer W surface in the Z-axis direction at aplurality of detection points that is detected by the multipoint AFsystem (90 a, 90 b) are loaded at a predetermined sampling intervalwhile wafer stage WST is proceeding in the +Y direction, and three kindsof information, which are each surface position information that hasbeen loaded and the measurement values of Y linear encoders 70F1 and70E1 at the time of each sampling, are made to correspond to one anotherand are sequentially stored in a memory (not shown).

Then, when the detection beams of the multipoint AF system (90 a, 90 b)begin to miss wafer W, main controller 20 ends the sampling describedabove and converts the surface position information at each detectionpoint of the multipoint AF system (90 a, 90 b) into data which uses thesurface position information by Z heads 72 a to 72 d that has beenloaded simultaneously as a reference.

More specifically, based on an average value of the measurement valuesof Z heads 72 a and 72 b, main controller 20 obtains the surfaceposition information of a predetermined point (for example, a pointcorresponding to a midpoint of the respective measurement points of Zheads 72 a and 72 b, that is, a point on substantially the same X-axisas the array of a plurality of detection points of the multipoint AFsystem (90 a, 90 b): hereinafter, this point is referred to as a leftmeasurement point P1) on an area (an area where Y scale 39Y₂ is formed)near the edge section on the −X side of plate 28. Further, based on anaverage value of the measurement values of Z heads 72 c and 72 d, maincontroller 20 obtains the surface position information at apredetermined point (for example, a point corresponding to a midpoint ofthe respective measurement points of Z heads 72 c and 72 d, that is, apoint on substantially the same X-axis as the array of a plurality ofdetection points of the multipoint AF system (90 a, 90 b): hereinafter,this point is referred to as a right measurement point P2) on an area(an area where Y scale 39Y₁ is formed) near the edge section on the +Xside of plate 28. Then, as shown in FIG. 9C, main controller 20 convertsthe surface position information at each detection point of themultipoint AF system (90 a, 90 b) into surface position data z1-zk,which uses a straight line that connects the surface position of leftmeasurement point P1 and the surface position of right measurement pointP2 as a reference. Main controller 20 performs such a conversion on allinformation taken in during the sampling.

By obtaining such converted data in advance in the manner describedabove, for example, in the case of exposure, main controller 20 measuresthe wafer table WTB surface (a point on the area where Y scale 39Y₂ isformed (a point near left measurement point P1 described above) and apoint on the area where Y scale 39Y₁ is formed (a point near rightmeasurement point P1 described above)) with Z heads 74 and 76 previouslydescribed, and computes the Z position and θy rotation (rolling) amountθy of wafer table WTB. Then, by performing a predetermined operationusing the Z position, the rolling amount θy, and the θx rotation(pitching) amount θx of wafer table WTB measured with Y interferometer16, main controller 20 computes the Z position (Z0) of the wafer tableWTB surface in the center (exposure center) of exposure area IApreviously described, or in other words, the Z position (Z0) of waferstage WST, rolling amount θy, and pitching amount θx, and based on thecomputation results, obtains a straight line passing through theexposure center that connects the surface position of left measurementpoint P1 and the surface position of right measurement point P2described above, and by using this straight line and surface positiondata z1 to zk, performs surface position control (focus levelingcontrol) of the upper surface of wafer W, without actually acquiring thesurface position information of the wafer W surface. Accordingly,because there is no problem even if the multipoint AF system is placedat a position away from projection optical system PL, the focus mappingof the embodiment can suitably be applied also to an exposure apparatusand the like that has a short working distance.

Further, in exposure apparatus 100 of the embodiment, a parallelprocessing operation using wafer stage WST and measurement stage MST,which includes focus mapping and the like described above, is performed,basically in the same procedure as the exposure apparatus disclosed inthe embodiment of the pamphlet of International Publication 2007/097379previously described. Because this parallel processing operation issimilar to the exposure apparatus disclosed in the embodiment of thepamphlet of International Publication 2007/097379 previously describedexcept for the following two points, a detailed description will beomitted.

The first point is, when abnormality occurs in the output of one of thepriority heads of the surface position measurement system 180 used formeasuring positional information of wafer stage WST in the Z directionand the θy direction in the case wafer stage WST is in the range wherethe stage moves for exposure operation, main controller 20 uses themeasurement values of the auxiliary head which configures a pair ofheads with the priority head as is previously described as themeasurement values of the pair of heads (or the head unit to which thetwo heads belong) in the Z-axis direction.

The second point is, for example, at the time of stepping operationbetween shots of wafer stage WST on the exposure operation by thestep-and-scan method, a switching of heads is performed by a switchingmethod in which the encoder head used for measuring the positionalinformation of wafer stage WST in the Z-axis direction and the θydirection is switched from a pair of heads (for example, Zh1 and Zh2) toanother pair of heads (Zh2 and Zh3) which include one of the heads(Zh2).

As discussed in detail above, according to exposure apparatus 100related to the embodiment, when wafer stage WST is located in the rangewhere wafer stage WST moves for exposure operation by the step-and-scanmethod, two Z heads each or more of the plurality of Z heads belongingto head units 62C and 62A constantly face Y scales 39Y₁ and 39Y₂,respectively, arranged on wafer stage WST. Therefore, main controller 20can constantly measure the positional information of wafer stage WST(wafer table WTB) in the Z-axis direction and rotation information(rolling amount) in the θy direction with high precision (without beingaffected by air fluctuation and the like), using the measurement resultsof at least one head (the priority head when the two Z heads are incorrespondence with the corresponding Y scales, or the auxiliary headwhen abnormality occurs in the output of the priority head) of the two Zheads each or more. Further, main controller 20 can measure the θxrotation of wafer table WTB with good accuracy, based on the measurementvalues of Y interferometer 16.

Further, according to exposure apparatus 100 related to the embodiment,by performing the focus leveling control of the water with high accuracyduring scanning exposure using the Z heads without measuring the surface position information of the wafer surface during exposure, based onthe results of focus mapping performed beforehand, it becomes possibleto form a pattern on wafer W with good precision. Furthermore, in theembodiment, because a high-resolution exposure can be realized by liquidimmersion exposure, a fine pattern can be transferred with goodprecision on wafer W also from this viewpoint.

Further, as is obvious from FIG. 6, of the plurality of Z heads 74 and76 respectively belonging to head units 62C and 62A used to control theZ position and θy rotation of water table WTB at the time of exposure,the position in the Y-axis direction of a part of the Z heads 74 ₆ to 74₉ and 76 ₁ to 76 ₄ is made to be different from other Z heads in thesame unit. Accordingly, the plurality of Z heads 74 and 76 belonging tohead units 62C and 62A can be placed at the empty spaces in theperiphery of projection unit PU, while avoiding nozzle unit 32, liquidsupply piping 31A, and liquid recovery piping 31B which configure a partof liquid immersion device 8. The same can be said for the Y headsbelonging to head units 62C and 62A. In this case, head unit 62C whichincludes Z head 74 and Y head 64 and head unit 62A which includes Z head76 and Y head 65 can be placed at the empty spaces in the periphery ofprojection unit PU without any problems, while the distance betweenadjacent Z heads (and Y heads 64 and 65) in the X-axis direction is setto a desired distance, as in, for example, distance WD, such as, forexample, 35 mm, which is narrower than half the width of Y scales 39Y₁and 39Y₂ in the X-axis direction (for example, 76 mm). Accordingly, theswitching between adjacent Z heads can be performed without any problemswhen wafer table WTB moves, and this also makes it possible to reducethe size of the entire apparatus.

In the embodiment above, while the case has been described where the Zheads belonging to head units 62A and 62C are used as a pair of headswith two heads forming a set, along with this, Z heads 72 a, 72 b, 72 c,and 72 d used at the time of focus mapping can each be configured by aset of two z heads (a pair of heads), and in the pair of heads, one ofthe heads can be a priority head, and when abnormality occurs in theoutput of the priority head, the Z head used for Z position control ofwafer stage WST can be switched to an auxiliary head.

MODIFIED EXAMPLE

Incidentally, in the embodiment above, two Z heads were constantlyfacing a common scale (reflection surface) so that the positionalinformation of wafer stage WST in the Z-axis direction can be measuredin a stable manner and with high precision. And, of a pair of headsconsisting of the two Z heads, measurement values of a priority head wasused, and in the case abnormality was generated in the measurement valueof the priority head due to malfunction of the head (or abnormality ofthe scale), measurement values of the other auxiliary head were to beused. However, as well as this, as a measurement method constantly usingthe two heads, which are the priority head and the auxiliary head,various modified examples can be considered.

Some representative examples will be shown below, which are modifiedexamples, referring to FIGS. 10A to 12. Incidentally, in FIGS. 10A to12, scale SY (more specifically, the wafer stage) is to be moved inthe—X-direction.

As a first modified example, two Z heads, which are a priority head anda auxiliary head, can be made into a set (to be referred to as a headset), and an example where at least one set is constantly made to facethe scale can be given. In this first modified example, as shown in FIG.10A, a head set Hs1 consisting of two Z heads Zh1 and Zh2 placed closeto the longitudinal direction (the Y-axis direction) of scale SY, andanother head set Hs2 consisting of two Z heads Zh3 and Zh4 placed closeto the Y-axis direction face one scale, SY. In this first modifiedexample, a plurality of head sets is prepared, configured of two Z headsin proximity to the Y-axis direction, and these head sets are placed inparallel with the X-axis direction at a distance smaller than theeffective width of scale SY. Accordingly, one head set will constantlyface scale SY.

When scale SY (more specifically, the wafer stage) moves in the −Xdirection from the state shown in FIG. 10A, head set Hs1 moves off ofscale SY. To be more precise, irradiation points of measurement beamsoutgoing from the two heads Zh1 and Zh2 constituting head set Hs1, ormore specifically, measurement points of heads Zh1 and Zh2 move off froman effective area of scale SY. Therefore, before head set Hs1 moves offfrom scale SY, main controller 20 switches the head set controlling thestage position from head set Hs1 to head set Hs2.

This first modified example is effective not only to abnormality of themeasurement values due to malfunction of the heads previously described,but is also effective to abnormality of the measurement values due toabnormality in the scales.

A second modified example following the first modified example describedabove is shown in FIG. 10B. As it can be seen when comparing FIGS. 10Band 10A, in the first modified example, a configuration was employedwhere the two Z heads configuring the head set each scanned a differentmeasurement point, whereas in the second modified example, aconfiguration is employed where the two Z heads configuring the head setscan the same measurement point. Accordingly, in the first modifiedexample, the two Z heads show different measurement values, whereas inthe second modified example, the two Z heads normally show measurementvalues equal to each other By employing the configuration in the secondmodified example, even if abnormality occurs in the measurement valuesof a priority head due to mechanical failure and the like in thepriority head, which is one of the two heads configuring the head set,the normal measurement values of the other head, or the auxiliary head,can be used as the measurement values of the head set Accordingly,abnormality is not detected in the measurement results as the head set.

Incidentally, the difference in the second modified example and thefirst modified example is only whether the position of the measurementpoint of the two Z heads configuring the head set is the same or not.Accordingly, the placement of each head set and the individual z headsconfiguring each head set in the second modified example should be setin a similar manner as the first modified example. By this arrangement,the procedure of the switching process also becomes the same.

In the first and second modified examples described above, the two Zheads configuring the head set is placed in parallel in the longitudinaldirection (Y-axis direction) of the scale. In correspondence with theseexamples, an example can also be considered where the placement is inparallel in a direction (the X-axis direction) orthogonal to thelongitudinal direction of the scale.

FIG. 11A shows a third modified example, in correspondence with thefirst modified example in FIG. 10A. In the third modified example,similar to the first modified example, two heads, which are a priorityhead and an auxiliary head, are made into a set, and at least one set isconstantly made to face the scale. However, in FIG. 11A, it is differentfrom the first modified example, and a head set Hs1 consisting of twoheads Zh1 and Zh2 placed close to the effective width direction (theX-axis direction) of scale SY, and another head set Hs2 consisting oftwo heads Zh3 and Zh4 placed close to the X-axis direction face onescale, SY. In this third modified example, a plurality of head sets isprepared, configured of two Z heads in proximity to the X-axisdirection, and these head sets are placed in parallel with the X-axisdirection so that one head set constantly faces scale SY.

When scale SY (more specifically, the wafer stage) moves in the −Xdirection from a state shown in FIG. 11A, the measurement point of Zhead Zh1 moves off from the effective area of scale SY. If, supposingthat Z head Zh1 was chosen as the priority head of head set Hs1, themain controller 20 switches the priority head to Z head Zh2 at a pointin time when Z head Zh1 moves off from scale SY. Furthermore, when scaleSY moves in the −X direction, then the measurement point of head Zh2moves off from scale SY. Therefore, by this point in time at the latest,or more specifically, before the measurement point of both heads Zh1 andZh2 configuring head set Hs1 moves off from scale SY, the head setcontrolling the stage position is switched from bead set Hs1 to head setHs2.

This third modified example, similar to the first modified example, iseffective not only to abnormality of the measurement values due tomalfunction of the heads previously described, but is also effective toabnormality of the measurement values due to abnormality in the scales.

A fourth modified example following the third modified example describedabove is shown in FIG. 11B. As it can be seen when comparing FIGS. 11Band 11A, in the third modified example, a configuration was employedwhere the two Z heads configuring the head set each scanned a differentmeasurement point, whereas in the fourth modified example, aconfiguration is employed where the same measurement point is scanned.Accordingly, in the third modified example, the two Z heads showdifferent measurement values, whereas in the fourth modified example,the two Z heads normally show measurement values equal to each other. Bythe configuration in the fourth modified example, even if abnormalityoccurs in the measurement values of a priority head of the two Z headsconfiguring the head set due to mechanical failure and the like in thepriority head, the normal measurement values of the other head, or theauxiliary head, can be used, therefore, abnormality is not detected inthe measurement results as the head set.

Incidentally, the difference in the fourth modified example and thethird modified example is only whether the position of the measurementpoint of the two Z heads configuring the head set is the same or notAccordingly, the placement of each head set and the individual Z headsconfiguring each head set in the fourth modified example should be setin a similar manner as the third modified example. By this arrangement,the procedure of the switching process also becomes the same.

Further, as is obvious when comparing FIGS. 11B and 10B, since thefourth modified example and the second modified example are differentmerely regarding the proximity direction of the two Z heads whichconfigure the head set, the effect that can be obtained is the same.

Further, in the third modified example in FIG. 11A, the distance of twoadjacent head sets, was set to a distance so that the irradiation points(measurement points) of the measurement beams outgoing from (all fourheads configuring) the two head sets were located within the effectivearea of scale SY. However, by reason of the switching process of theheadset, the placement distance of the two adjacent headsets can be setto a placement distance in which the two Z heads (Zh3, Zh4) configuringone head set (Hs2) and one of the Z heads (Zh2) of the two heads (Zh1,Zh2) configuring the other head set (Hs1), or three Z heads (Zh2, Zh3,and Zh4), face scale SY, as shown in FIG. 12.

Incidentally, in the tour modified examples, while a head set consistingof one priority head and one auxiliary head was used, the number ofauxiliary heads is not limited to one, and a plurality of auxiliaryheads can be arranged. In the case of using an encoder head having sucha configuration, reliability of the measurement results improves becausemore measurement data can be detected. Further, in the case theplurality of heads within the head set are observed to be at the sameposition in the transverse direction (the X-axis direction in themodified examples) of the scale as in the four modified examples,priority cannot be given according to the guidelines such as, “prioritygiven to the head which becomes effective first,” or “priority given tothe head closer to the scale center.” Accordingly, it is desirable todecide a fixed priority order in the headset in advance.

Incidentally, the configuration of each measurement device such as thesurface position measurement system described in the embodiment above isonly an example, and it is a matter of course that the present inventionis not limited to this. For example, in the embodiment above, while anexample has been described where a surface position measurement systemwas employed that has a configuration of having a reflection surface (Yscale) arranged on the wafer table (wafer stage) and a Z head placedfacing the reflection surface external to the wafer stage, a surfaceposition measurement system having a configuration of a Z head beingarranged on the wafer stage and a reflection surface arranged externalto the wafer stage facing the Z head can also be employed. In this case,at least two encoder heads can be arranged on a plurality of places onthe wafer stage, for example, on the four corners, and with one of theat least two encoder heads serving as a priority head and the remainingat least one encoder head serving as an auxiliary head, position controlof the wafer stage can be performed similarly as in the embodiment andthe modified examples above. Incidentally, the at least two encoderheads can be placed in proximity on the wafer stage, or can be placed apredetermined distance apart. Especially in the latter case, the headscan be placed along a radiation direction from the center of the waferstage.

Further, because the surface of the reflection surface arranged externalto the wafer stage faces downward, the liquid of the liquid immersionarea will not remain and foreign materials such as dust and the likewill not adhere on the surface. Accordingly, because abnormality of theZ head output due to the abnormality of the reflection surface does nothave to be considered, the controller which performs the switching ofthe heads can decide to monitor only the output abnormality of thepriority head due to the malfunction of the head.

Further, in the embodiment and the modified examples above, while thecase has been described where the encoder head and the Z head wereseparately arranged, every encoder head can have a Z head, or eachencoder head can be equipped with a Z head, or each encoder head can bea head (sensor) that can perform position detection in two directions,which are the X-axis or Y-axis direction, and the Z-axis directionEspecially in the former case, the encoder head and the Z head can beintegrally arranged.

Further, in the embodiment and the modified examples above, malfunction(abnormality) of the encoder head includes gradient of the head or lossof telecentricity, besides mechanical failure. Further, in the case ofthe type of encoder system which has a head arranged on the stage and ascale arranged above the head, the case when foreign materials(including, for example, the liquid for liquid immersion) adhere on thehead is included in the abnormality (malfunction) of the encoder head.Further, not only in the case when the position becomes unmeasurable,but the case when the measurement accuracy exceeds a permissible value(the output (intensity) of the encoder head results to be outside thepermissible range) is also included in the abnormality of the encoderhead.

Further, in the embodiment above, while the case has been describedwhere head units 62A and 62C each are equipped with nine Z heads, thenumber is not an issue as long as there are two or more Z heads whichcan simultaneously face a pair of reflection surfaces (in the embodimentabove, Y scales 39Y₁ and 39Y₂) arranged on both sides of projectionunits.

Further, because rotation information in the θy direction of wafer tableWTB (wafer stage WST) can also be measured using Z interferometers 43Aand 43B, or X interferometer 126, the Z head can be arranged in aplurality of numbers on either one of head units 62A or 62C. From asimilar point, if the Y scale which is the measurement object of the 2head is used only for the purpose of measuring the Z position of wafertable WTB, only one of Y scales 39Y₁ and 39Y₂ arranged is enough.Further, as the measurement object of the Z head, instead of Y scales39Y₁ and 39Y₂, an exclusive reflection surface can be formed on theupper surface of wafer table WTB.

Further, in the embodiment above, while the case has been describedwhere Z heads 74 and 76 were placed avoiding nozzle unit 32 and the likeconfiguring a part of the liquid immersion system, in the case aplurality of sensor heads are arranged in a straight line parallel tothe X-axis, it is desirable to at least move some sensor heads from thestraight line in order to avoid the structures that are located on thestraight line. As such a structure, besides projection optical unit PUand its peripheral members, at least a part of multipoint AF system (90a, 90 b), or at least a part of alignment systems AL1 and AL2 _(n) canbe representatively given. In the embodiment above, Z heads 72 a to 72 dare placed, avoiding multipoint AF system (90 a, 90 b).

Incidentally, in the embodiment above, while the lower surface of nozzleunit 32 and the lower end surface of the tip optical element ofprojection optical system PL were substantially flush, as well as this,for example, the lower surface of nozzle unit 32 can be placed nearer tothe image plane (more specifically, to the wafer) of projection opticalsystem PL than the outgoing surface of the tip optical element. That is,the configuration of local liquid immersion device 8 is not limited tothe configuration described above, and the configurations which aredescribed in, for example, EP Patent Application Publication No.1420298, U.S. patent Application Publication 2006/0231206, U.S. patentApplication Publication 2005/0280791, and U.S. Pat. No. 6,952,253 andthe like can also be used. Further, as disclosed in, for example, U.S.patent Application Publication No. 2005/0248856, the optical path on theobject plane side of the tip optical element can also be filled withliquid, in addition to the optical path on the image plane side of thetip optical element. Furthermore, a thin film that is lyophilic and/orhas dissolution preventing function may also be formed on the partialsurface (including at least a contact surface with liquid) or the entiresurface of the tip optical element. Incidentally, quartz has a highaffinity for liquid, and also needs no dissolution preventing film,while in the case of fluorite, at least a dissolution preventing film ispreferably formed.

Incidentally, in the embodiment above, pure water (water) was used asthe liquid, however, it is a matter of course that the present inventionis not limited to this. As the liquid, a chemically stable liquid thathas high transmittance to illumination light IL and is safe to use, suchas a fluorine-containing inert liquid can be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 can be used. As this typeof liquid, for example, a predetermined liquid having C-H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of these liquids may be used, or aliquid obtained by adding (mixing) at least one of these liquids to(with) pure water may be used. Alternatively, as the liquid, a liquidobtained by adding (mixing) base or acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄²⁻, or PO₄ ²⁻ to (with) pure water can be used. Moreover, a liquidobtained by adding (mixing) particles of Al oxide or the like to (with)pure water can be used. These liquids can transmit ArF excimer laserlight. Further, as the liquid, liquid, which has a small absorptioncoefficient of light, is less temperature-dependent, and is stable to aprojection optical system (tip optical member) and/or a photosensitiveagent (or a protection film (top coat film), an antireflection film, orthe like) coated on the surface of a wafer, is preferable. Further, inthe case an F₂ laser is used as the light source, fomblin oil can beselected. Further, as the liquid, a liquid having a higher refractiveindex to illumination light IL than that of pure water, for example, arefractive index of around 1.6 to 1.0 may be used. As the liquid,supercritical fluid can also be used. Further, the tip optical elementof projection optical system PL may be formed by quartz (silica), orsingle-crystal materials of fluoride compound such as calcium fluoride(fluorite), barium fluoride, strontium fluoride, lithium fluoride, andsodium fluoride, or may be formed by materials having a higherrefractive index than that of quartz or fluorite (e.g. equal to orhigher than 1.6). As the materials having a refractive index equal to orhigher than 1.6, for example, sapphire, germanium dioxide, or the likedisclosed in the pamphlet of International Publication No. 2005/059617,or kalium chloride (having a refractive index of about 1.75) or the likedisclosed in the pamphlet of International Publication No. 2005/059618can be used.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery unit, a recovery pipeor the like.

Further, in the embodiment above, the case has been described where theexposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, but can also beemployed in a dry type exposure apparatus that performs exposure ofwafer W without liquid (water).

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Even in the case of a stepper, because the Z positionof the wafer table on which the object subject to exposure is mountedcan be measured using a Z head as in the embodiment described above, asimilar effect can be obtained. Further, the present invention can alsobe applied to a reduction projection exposure apparatus by astep-and-stitch method that synthesizes a shot area and a shot area, anexposure apparatus by a proximity method, a mirror projection aligner,or the like. Moreover, the present invention can also be applied to amulti-stage type exposure apparatus equipped with a plurality of waferstages, as is disclosed in, for example, the U.S. Pat. No. 6,590,634,the U.S. Pat. No. 5,969,441, the U.S. Pat. No. 6,208,407 and the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatodioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Further, the illumination areaand exposure area described above are to have a rectangular shape.However, the shape is not limited to rectangular, and can also becircular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr2 laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm), an i-line (wavelength: 365 nm) and the like canalso be used. Further, a harmonic wave generating unit of a YAG laser orthe like can also be used. Besides the sources above, as is disclosedin, for example, U.S. Pat. No. 7,023,610, a harmonic wave, which isobtained by amplifying a single-wavelength laser beam in the infrared orvisible range emitted by a DFB semiconductor laser or fiber laser asvacuum ultraviolet light, with a fiber amplifier doped with, forexample, erbium (or both erbium and ytteribium), and by converting thewavelength into ultraviolet light using a nonlinear optical crystal, canalso be used.

Further, in the embodiment above, illumination light TL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm can be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOR or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (forexample, 13.5 nm) and the reflective mask has been developed. In the EUVexposure apparatus, the arrangement in which scanning exposure isperformed by synchronously scanning a mask and a wafer using a circulararc illumination can be considered, and therefore, the present inventioncan also be suitably applied to such an exposure apparatus. Besides suchan apparatus, the present invention can also be applied to an exposureapparatus that uses charged particle beams such as an electron beam oran ion beam.

Further, in the embodiment above, a transmissive type mask (reticle) isused, which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed. Instead of this reticle, however, as is disclosed in, forexample, U.S. Pat. No. 6,778,257, an electron mask (which is also calleda variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed can also be used.

Further, for example, the present invention can also be applied to anexposure apparatus (lithography system) that forms line-and-spacepatterns on a wafer by forming interference fringes on the wafer.

Moreover, as disclosed in, for example, U.S. Pat. No. 6,611,316, thepresent invention can also be applied to an exposure apparatus thatsynthesizes two reticle patterns via a projection optical system andalmost simultaneously performs double exposure of one shot area by onescanning exposure.

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The use of the exposure apparatus is not limited only to the exposureapparatus for manufacturing semiconductor devices, but the presentinvention can also be widely applied, for example, to an exposureapparatus for transferring a liquid crystal display device pattern ontoa rectangular glass plate, and an exposure apparatus for producingorganic ELs, thin-film magnetic heads, imaging devices (such as CCDs),micromachines, DNA chips, and the like. Further, the present inventioncan be applied not only to an exposure apparatus for producingmicrodevices such as semiconductor devices, but can also be applied toan exposure apparatus that transfers a circuit pattern onto a glassplate or silicon wafer to produce a mask or reticle used in a lightexposure apparatus, an EUV exposure apparatus, an X-ray exposureapparatus, an electron-beam exposure apparatus, and the like.

Incidentally, the disclosures of the various publications, the pamphletsof the International Publications, and the U.S. patent ApplicationPublication descriptions and the U.S. patent descriptions that are citedin the embodiment above and related to exposure apparatuses and the likeare each incorporated herein by reference.

Electronic devices such as semiconductor devices are manufacturedthrough the steps of; a step where the function/performance design ofthe device is performed, a step where a reticle based on the design stepis manufactured, a step where a wafer is manufactured from siliconmaterials, a lithography step where the pattern of a reticle istransferred onto the wafer by the exposure apparatus (pattern formationapparatus) in the embodiment previously described, a development stepwhere the wafer that has been exposed is developed, an etching stepwhere an exposed member of an area other than the area where the resistremains is removed by etching, a resist removing step where the resistthat is no longer necessary when etching has been completed is removed,a device assembly step (including a dicing process, a bonding process,the package process), inspection steps and the like. In this case, inthe lithography step, because the device pattern is formed on the waferby executing the exposure method previously described using the exposureapparatus of the embodiment, a highly integrated device can be producedwith good productivity.

While the above-described embodiments of the present invention are thepresently preferred embodiments thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

1. A movable body apparatus including a movable body which substantiallymoves along a predetermined plane, the apparatus comprising; areflection surface which is arranged at one of the movable body and theoutside of the movable body, with a first direction within a planeparallel to the predetermined plane serving as a longitudinal direction,and having a predetermined width in a second direction orthogonal to thefirst direction; and a measurement device which measures positionalinformation of the movable body in a third direction orthogonal to thepredetermined plane at a plurality of measurement points placed on thereflection surface, whereby the placement of the plurality ofmeasurement points is decided so that of the plurality of measurementpoints, n points (wherein, n is an integer of two or more) or more arepositioned within the predetermined width on the reflection surface, andwhen the movable body is at a predetermined position, n+1 or more of theplurality of measurement points are positioned to be within thepredetermined width on the reflection surface.
 2. The movable bodyapparatus according to claim 1 wherein the reflection surface isarranged on a surface substantially parallel to the predetermined planeof the movable body.
 3. The movable body apparatus according to claim 1,the apparatus further comprising; a controller which performs positioncontrol of the movable body, preferentially using a first measurementinformation including measurement information at a first measurementpoint out of the n points or more measurement points positioned withinthe predetermined width on the reflection surface or the n+1 or moremeasurement points positioned within the predetermined width on thereflection surface when the movable body is at the predeterminedposition, whereby the controller switches measurement information topreferentially use in position control of the movable body to a secondmeasurement information including measurement information at a secondmeasurement point which is different from the first measurement point,in the case abnormality occurs in the measurement information at ameasurement point positioned within the predetermined width of thereflection surface.
 4. The movable body apparatus according to claim 3wherein the controller switches measurement information to use inposition control of the movable body to the second measurementinformation when abnormality occurs in the measurement information atthe first measurement point.
 5. The movable body apparatus according toclaim 3 wherein each of the first measurement information and the secondmeasurement information include measurement information at a pluralityof measurement points.
 6. The movable body apparatus according to claim3 wherein each of the first measurement information and the secondmeasurement information are measurement information at one measurementpoint.
 7. The movable body apparatus according to claim 3 wherein themeasurement device has a plurality of heads which irradiate measurementbeams on a measurement point, and the controller performs the switchingwhen abnormality in measurement information occurs due to malfunction ofthe heads.
 8. The movable body apparatus according to claim 1 whereinthe measurement device has a plurality of heads which irradiatemeasurement beams on a measurement point, and each of the plurality ofheads irradiate the measurement beams on different measurement points.9. The movable body apparatus according to claim 2 wherein in themovable body, the reflection surface is arranged apart in a pair in thesecond direction, and the placement of the measurement points is decidedso that n or more measurement points are constantly positioned in atleast one of the pair of reflection surfaces when the movable body is inthe predetermined range within the predetermined plane.
 10. The movablebody apparatus according to claim 1 wherein the measurement points areplaced in the second direction, each spaced apart by half or less thanhalf the predetermined width of the reflection surface at asubstantially equal distance.
 11. The movable body apparatus accordingto claim 1 wherein the measurement device has a first and second headwhich irradiate measurement beams on the same measurement point, and anirradiation area of the measurement beam irradiated from the first headis in proximity with an irradiation area of the measurement beamirradiated by the second head, without overlapping.
 12. A patternformation apparatus that forms a pattern on an object, the apparatuscomprising: a patterning device which forms a pattern on the object, andthe movable body apparatus according to claim 1 in which the object ismounted on the movable body.
 13. The pattern formation apparatusaccording to claim 12 wherein the object has a sensitive layer, and thepatterning device forms a pattern on the object by exposing thesensitive layer.
 14. An exposure apparatus that forms a pattern on anobject by irradiating an energy beam, the apparatus comprising: apatterning device that irradiates the energy beam on the object; themovable body apparatus according to claim 1 in which the object ismounted on the movable body, and a driver which drives the movable bodyto make the object relatively move with respect to the energy beam. 15.A device manufacturing method which uses the exposure apparatusaccording to claim
 14. 16. A movable body apparatus including a movablebody which substantially moves along a predetermined plane, theapparatus comprising: a reflection surface which is arranged at one ofthe movable body and the outside of the movable body, with a firstdirection within a plane parallel to the predetermined plane serving asa longitudinal direction, and having a predetermined width in a seconddirection orthogonal to the first direction; and a measurement devicewhich measures positional information of the reflection surface in athird direction orthogonal to the predetermined plane at a plurality ofmeasurement points plated on the reflection surface, whereby themeasurement device has a plurality of head sets including a first headwhich irradiates a measurement beam on a first measurement point and asecond head which irradiates a measurement beam on the first measurementpoint or in its vicinity.
 17. The movable body apparatus according toclaim 16 wherein the reflection surface is arranged on a surfacesubstantially parallel to the predetermined plane of the movable body.18. The movable body apparatus according to claim 16 wherein measurementpoints on which the measurement beams are irradiated by the first headand the second head are placed, each by a predetermined width, at asubstantially equal distance.
 19. The movable body apparatus accordingto claim 16 wherein in the measurement device, at least a part of ameasurement area where the measurement beam of the first head irradiatesoverlaps a part of a measurement area where the measurement beam of thesecond head irradiates.
 20. The movable body apparatus according toclaim 16, the apparatus further comprising: a controller which controlsa position of the movable body preferentially using measurementinformation generated by the first head, and also switches themeasurement information preferentially used from the measurementinformation generated by the first head to measurement informationgenerated by the second head in the case abnormality occurs in themeasurement information generated by the first head.
 21. The movablebody apparatus according to claim 20 wherein the controller performs theswitching when abnormality in measurement information occurs due tomalfunction of the heads.
 22. A pattern formation apparatus that forms apattern on an object, the apparatus comprising: a patterning devicewhich forms a pattern on the object, and the movable body apparatusaccording to claim 16 in which the object is mounted on the movablebody.
 23. The pattern formation apparatus according to claim 22 whereinthe object has a sensitive layer, and the patterning device forms apattern on the object by exposing the sensitive layer.
 24. An exposureapparatus that forms a pattern on an object by irradiating an energybeam, the apparatus comprising: a patterning device that irradiates theenergy beam on the object; the movable body apparatus according to claim16 in which the object is mounted on the movable body; and a driverwhich drives the movable body to make the object relatively move withrespect to the energy beam.
 25. A device manufacturing method which usesthe exposure apparatus according to claim
 24. 26. A movable bodyapparatus including a movable body which substantially moves along apredetermined plane, the apparatus comprising: a measurement devicewhich measures positional information of the movable body in a directionorthogonal to the predetermined plane, at a plurality of measurementpoints placed in a movement range of the movable body, whereby themeasurement device has a plurality of heads which generate measurementinformation by irradiating a measurement beam on at least one of theplurality of measurement points when the movable body is located at apredetermined position.
 27. The movable body apparatus according toclaim 26 wherein the head is placed at the movable body.
 28. The movablebody apparatus according to claim 26 wherein the movable body has areflection surface which reflects the measurement beam irradiated fromthe head.
 29. The movable body apparatus according to claim 26 whereinthe plurality of heads include a first head and a second head whichirradiate measurement beams on the same one measurement point of theplurality of measurement points when the movable body is at thepredetermined position, and at the measurement point, at least a part ofan irradiation area of the measurement beam irradiated from the firsthead overlaps at least a part of an irradiation area of the measurementbeam irradiated from the second head.
 30. The movable body apparatusaccording to claim 26 wherein the plurality of heads include a firsthead and a second head which irradiate measurement beams on the same onemeasurement point of the plurality of measurement points when themovable body is at the predetermined position, and at the measurementpoint, an irradiation area of the measurement beam irradiated from thefirst head is in proximity with an irradiation area of the measurementbeam irradiated from the second head, without overlapping.
 31. Themovable body apparatus according to claim 26 wherein the plurality ofheads include a first head and a second head which irradiate measurementbeams on the same one measurement point of the plurality of measurementpoints when the movable body is at the predetermined position, and theapparatus further comprises; a controller which controls a position ofthe movable body preferentially using measurement information generatedby the first bead of the plurality of heads irradiating measurementbeams on the same measurement point, and also switches the measurementinformation preferentially used from the measurement informationgenerated by the first head to measurement information generated by thesecond head of the plurality of heads in the case abnormality occurs inthe measurement information generated by the first head.
 32. The movablebody apparatus according to claim 31 wherein the controller performs theswitching when abnormality in measurement information occurs due tomalfunction of the heads.
 33. A pattern formation apparatus that forms apattern on an object, the apparatus comprising: a patterning devicewhich forms a pattern on the object, and the movable body apparatusaccording to claim 26 in which the object is mounted on the movablebody.
 34. The pattern formation apparatus according to claim 33 whereinthe object has a sensitive layer, and the patterning device forms apattern on the object by exposing the sensitive layer.
 35. An exposureapparatus that forms a pattern on an object by irradiating an energybeam, the apparatus comprising: a patterning device that irradiates theenergy beam on the object; the movable body apparatus according to claim26 in which the object is mounted on the movable body, and a driverwhich drives the movable body to make the object relatively move withrespect to the energy beam.
 36. A device manufacturing method which usesthe exposure apparatus according to claim 35.